Circle Math

What is the formula for calculating the circumference of a circle?

• π * r

• 2 * r

• π * r^2

• 2 * π * r

If the circumference of a circle is 20π, what is the radius?

• 5

• 10

• 25

• 15

Calculate the circumference of a circle with a diameter of 10 units.

• 20 units

• 15.7 units

• 31.42 units

• 8 units

What is the formula for calculating the area of a circle?

• 3.14r^2

• πr^2

• 2πr

• r/2

Find the area of a circle with a radius of 5 units.

• 78.54 square units

• 10.5 square units

• 15.7 square units

• 25.12 square units

If the area of a circle is 64π, what is the radius?

• 12

• 16

• 8

• 4

Calculate the area of a circle with a diameter of 14 units.

• 153.94 square units

• 196 square units

• 7 square units

• 28 square units

If the circumference of a circle is 36π, what is the diameter?

• 12

• 36

• 72

• 18

A circular swimming pool has a circumference of 66 feet. What is the radius of the pool?

• 5.25 feet

• 20 feet

• 15 feet

• 10.5 feet

A circular garden has an area of 154π square meters. What is the diameter of the garden?

• 10 meters

• 18 meters

• 14 meters

• 22 meters